Trends to reduce noise pollution and provide quiet interior spaces encourage the use of sound reducing materials, creating a growing market for acoustical building materials. However, there is also a desire for an aesthetically pleasing finish, since at least one surface of the sound reducing material is visible from inhabited areas.
Traditional plaster has a smooth monolithic appearance that is considered to be a model surface. It accepts a variety of decorative finishes, such as paint, wallpaper, and the new faux finishes. However, the plaster also reflects sound, thereby increasing noise pollution. Some sound frequencies are also distorted, making the reflected sounds even less desirable.
Conventional acoustical panels are well-suited for absorbing sounds. The surface of the panel is treated to provide openings into which sounds penetrate. For example, the panel may be needled, that is, it is punctured with rows of needles that create pores in the panel surface. When combined with a porous panel structure, the sounds enter the needle voids and pass into the panel pores. As the sounds reflect off the walls of the voids or pores, a portion of the sound is absorbed. This results in little or no sound exiting the panel. However, the aesthetics of the panels are not widely accepted and consumers are looking for an acoustical panel without visible holes or fissures.
There are other acoustical systems commercially available that deliver both an aesthetically pleasing finish and sound attenuation. However, the systems require fixing of a specialty fiberglass mat to the substrate with an adhesive, treatment of the joints and application of a finish-coat plaster by hand. Thus, these systems have several disadvantages. The specialty fiberglass panel must be purchased and transported to the job site without damage. A large number of specialty supplies are needed, including the panel, adhesive and at least two types of acoustical plaster. At least four time-consuming steps are needed for installation of the panel, such as preparing the panel, adhering the panel, treating the joints and applying the plaster.
Thus, it would be advantageous to design a system for finishing a substrate that provides both improved sound absorbency and an aesthetically pleasing surface.